SE430700B - MAGNESIUM ALLOY COMPOSITE REINFORCED WITH SILICON CARBID FIBERS AND SET TO MAKE IT - Google Patents

Description

aanmáfoza-aa products. When magnesium alloys are used as a forging material, magnesium hexagonal has a tightly packed structure, so that the cold workability is poor in comparison with aluminum and copper with cubic crystal. Therefore, the need for magnesium and magnesium alloys has been scarce until recently. Since the Second World War, the speed of aircraft has increased and jet engines have evolved rapidly, and since magnesium has low weight and the disadvantage of being difficult to cause to slip during processing is considered a merit as the deformation is quite difficult to achieve at high temperature, magnesium as a heat-resistant light alloy has been significant and the study of heat-resistant magnesium alloys has been extensive.

The study has been done with respect to the corrosion resistance which is a deficiency of magnesium and recently the quality of the base metal has been significantly improved by developing a method of wrapping magnesium, so that the corrosion resistance of magnesium has become very high and the crystal grains have been made very fine by adding zirconium and similar and it has been possible to produce faultless castings with a reliable pressure resistance. Furthermore, by adding rare earth metals such as cerium, mixed metal, thorium, etc., heat-resistant magnesium alloys with very excellent creep at high temperature have been produced and various properties of magnesium alloys have been significantly improved.

In addition, it has been proposed to change the inherent hexagonal densely packed structure of magnesium to cubic crystal structure by adding lithium to increase the cold workability.

Heretofore, the study of the composite material consisting of silicon carbide fibers and magnesium alloy has been conducted with respect to silicon carbide whiskers and magnesium alloy because in practice silicon carbide fibers used have been whiskers. However, silicon carbide whiskers consisting of SiC alone have poor wettability against magnesium alloy and the length of said whiskers is a few mm at most, so it is very difficult to arrange these whiskers regularly, the tensile strength is weak, the modulus of elasticity is low and the cost is high, why An object of the present invention is to avoid the various disadvantages described above of magnesium alloy composite materials reinforced with silicon carbide whiskers and to provide magnesium alloy composite materials reinforced with cohesive high temperature silicon carbide fibers. and a high modulus of elasticity.

Another object is to provide a method of producing the composite materials described above using new, cohesive silicon carbide fibers as reinforcing fibers. It has now been discovered that when a composite material is made from the new silicon carbide fibers having high strength and containing at least 0.01% by weight of free carbon and magnesium alloy the mutual wettability of the two substances is improved and the object of the present invention is achieved.

The silicon carbide fibers containing at least 0.01% by weight of free carbon, which are to be used for the production of the composite materials according to the present invention, are prepared in the manner described in Swedish patent application 7604699-4.

The reason why silicon carbide fibers containing at least 0.01% by weight of free carbon are used in the production of magnesium alloy composite materials reinforced with silicon carbide fibers according to the present invention is that silicon carbide fibers containing less than 0.01% by weight of free carbon have poor wettability to magnesium alloy. and even when the composite material is produced, when such composite material is exposed to temperature and external force, the mutual reinforcing effect can not develop due to the gap between the fibers and the metal matrix.

In the present invention, silicon carbide fibers containing 1 to 40% by weight of free carbon can be used.

Until the amount of free carbon in the kiseicarbia fibers is so folded, the tensile strength of the composite material increases and when the amount is 5-20% by weight, the tensile strength gradually decreases. When the amount of free carbon exceeds 20% by weight, the tensile strength of the composite material decreases sharply.

The modulus of elasticity of the composite material mainly does not vary when the amount of free carbon is above 1% by weight.

When using magnesium alloy composite materials, the free carbon in the silicon carbide fibers reacts with the elements added to the magnesium alloy to form a carbide of the alloying element on the surface of the silicon carbide fibers, presumably obtaining chemical adhesion instead of chemical adhesion.

In the above-described reaction of the free carbon with an element added to a magnesium alloy, carbon diffuses from the inner part of the silicon carbide fibers containing the free carbon to the surface and reacts with an element added to a magnesium alloy, and furthermore an element added to a magnesium alloy, diffuses into the inner part of the silicon carbide fibers and reacts with the free carbon, so that the wettability of the silicon carbide fibers and an element added to a magnesium alloy becomes very good. The reaction of the free carbon with an element added to a magnesium alloy is very fast, but the diffusion rate at which the free carbon diffuses from the inner part of the silicon carbide fibers, and the diffusion rate with which an element added to a magnesium alloy diffuses into the inner part of the silicon carbide fibers is low, that the molten metal and the silicon carbide fibers containing why it is generally suitable for the free carbon to be contacted and reacted for more than 10 minutes.

However, when composite materials made using silicon carbide fibers containing a large amount of free carbon are used at a relatively high temperature for a long period of time, the free carbon in the silicon carbide fibers reacts with the metal element in the metal matrix, which is adapted to form a carbide, to form of a carbide, whereby the mechanical strength of the silicon carbide fibers is not only reduced but also the composition and the mechanical strength of the matrix itself varies gradually, in particular the brittleness increases.

Especially when silicon carbide fibers containing more than 5% by weight of free carbon are used, this tendency appears, and when the amount of free carbon is above 20 vixcæ, the harmful effect of the carbide-forming reaction becomes significant, and the tensile strength of the composite material decreases. It is due to the hardening effect of the formed carbide that the modulus of elasticity does not vary, even if the amount of free carbon in the silicon carbide fibers varies. Consequently, in the case of silicon carbide fibers containing a large amount of free carbon, it is necessary to inhibit the carbide formation reaction while maintaining the wettability. When the surface of the silicon carbide fibers is covered with a metal or ceramic material having a2o14os-5 moderate bonding ability to the fibers, the covered fibers can strengthen the magnesium alloy matrix and can prevent the change in the physical and chemical properties of the matrix, which is achieved by the diffusion of the free the matrix described above, the composite materials in which the properties do not significantly deteriorate, even if the composite material is used for a long period of time at a high temperature.

The silicon carbide fibers to be used in the present invention are prepared by spinning high molecular weight organic silicon compounds and burning the spun fibers to obtain cohesive silicon carbide fibers, but during the manufacturing process, if the step of disposing of or disposing of carbon can be the cohesive silicon carbide fibers containing less than about 40% free carbon are obtained.

In the following, a method of producing the silicon carbide fibers and their properties will be described.

The silicon carbide fibers containing 0.01-40% by weight of free carbon, which are to be used in the present invention, can be prepared from the following organic silicon compounds (1) - (10). (1) Compounds with Si-C bond only. (2) Compounds with Si-H bond and Si-C bond. (3) Compounds with Si-Hal bonding. (4) Compounds with Si-N bond. (5) Compounds having Si-Okr bond (R: alkyl or aryl group). (6) Compounds with Si-OH bond. (7) Compounds with Si-Si bonding. (8) Compounds with Si-O-Si bonding; (9) Esters of organic silicon compounds, and (10) Peroxides of organic silicon compounds. At least one of the organic silicon compounds belonging to the above-described groups (1) - (10) is subjected to polycondensation reaction using at least one of irradiation, heating and addition of polycondensation catalyst to form high molecular weight organic silicon compounds having silicon and carbon as main skeletal components. For example, the compounds are prepared with the following molecular structures. å fi- "áï fi ßfüâ-S '(a) -% if%) n-% io-. | (b) -s1-o - (?> no- | t (C) -§i- (§) n- ( d) The compounds having the above-described skeletal components (a) -§c) which form at least a substructure in linear, ring and three-dimensional structures or a mixture of the compounds with the above-described skeletal components (a) - (c) .

The compounds with the molecular structures described above are, for example, as follows.

CH3 I CH3 '' (a) -Si- (C) n'5i'Q 'CH3 H3 n = 1, poly (silmethylenesiloxane), n = 2, poly (silethylensiloxane), n = 6, poly (silphenylensiloxane), CH3 (b) -i-o- (c) n-o- I CH 3 n = 1, poly (methylenoxysiloxane), β, poly (ethyleneoxysiloxane), an = 6, poly (phenylenoxysiloxane); n = 12, polyIdiphenyleneoxysiloxane and CH3 (C) -Si- (C) n CH3 n = 1, polysilmethylene, n = 2, polysiletylene, 9201408-s (d) The compounds having the skeletal components described above as at least one substructure in linear, annular and three-dimensional structures, or mixtures of the compounds with the above-described skeletal components (ä) - (C) »The high molecular weight organic silicon compounds described above are spun and the spun fibers are first heated under an oxidizing atmosphere and then burned at a high temperature under at least one atmosphere of vacuum, inert gas, CO gas and hydrogen gas to form silicon carbide fibers with a very high strength and a high modulus of elasticity.

The ratio of silicon to carbon present in the above-described high molecular weight organic silicon compounds (a) - (d), which are the starting material for the above-described cohesive silicon carbide fibers, is two silicon atoms per at least five carbon atoms, so that when the organic silicon compounds high molecular weight is spun and the spun fibers burn many carbon atoms are bound when the side chain of the high molecular weight compounds is volatilized, such as hydrocarbons or organic silicon compounds, but 0.01-40% by weight of carbon remains as free carbon in the silicon carbide fibers.

If the content of free carbon in the silicon carbide fibers is less than 0.01% by weight, the amount of free carbon which diffuses from the inner part of the silicon carbide fibers into the metal matrix and reacts with the matrix metal is too low, so that the tensile strength of the light metal composite materials is enhanced. with the silicon carbide fibers, does not improve. Silicon carbide fibers prepared from the high molecular weight organic silicon compounds may not contain more than 40% by weight of free carbon. Accordingly, the content of free carbon present in the silicon carbide fibers to be used for the production of the light metal composite materials reinforced with the silicon carbide fibers must be 0.01-40% by weight.

The tensile strength and modulus of elasticity of the silicon carbide fibers to be used in the present invention are given in the following table, and silicon carbide fibers having such high tensile strength are previously unknown. eaanèos-s g ß TABLE Tensile strength 300 - 600 kp / mmz Specific strength approx. 4.0 x 107 cm Module of elasticity approx. 20 - 40 t / mmz 'Specific modulus of elasticity approx. 1.0 x 109 cmf E The modulus of elasticity of the silicon carbide fibers according to the present invention is mainly same as that of carbon fibers, which has the highest modulus of elasticity among currently known fibers.

Magnesium alone is hardly used as an industrial and construction material and is used only as magnesium alloys, but when a composite material is made from a magnesium alloy and the silicon carbide fibers, the free carbon in the silicon carbide fibers reacts with a metal present in the magnesium alloy adapted to form a carbide. eg Al, Mn, Zr, Si, Ca, Y and other rare earth metals, Th etc., to form carbides. In this case, when an amount of the formed carbide is small, the formed carbide has no major effect on the mechanical properties of the metal matrix, but when said amount becomes large, the mechanical properties, especially the toughness of the metal matrix, decrease, and the formed composite material becomes cracked. Particularly in the case of composite materials consisting of a heat-resistant magnesium alloy and the silicon carbide fibers containing more than 5% free carbon, during the use of the composite materials at a high temperature, the formation reaction of the carbides described above proceeds, and when such composite materials are used for a long time. hand brittle.

Even if zinc or beryllium are present in the magnesium alloy, these elements do not prevent the formation of the carbide with the free carbon in the silicon carbide fibers, so it is not necessary to take into account the influence of these metals.

When the composite materials are prepared using the silicon carbide fibers containing the free carbon in an amount above the amount necessary to improve the wettability of the silicon carbide fibers to the matrix, the surfaces are coated with such silicon carbide fibers with a metal or ceramic material to prevent the free reaction between the carbon in the silicon carbide fibers and the matrix metal, which exceeds the necessary degree, and in order to maintain the inherent properties of the metal matrix and reinforce the metal matrix with the cohesive silicon carbide fibers, after which the magnesium alloy matrix is reinforced with the a composite material.

In particular, if a composite material made using the silicon carbide fibers containing 5-40% by weight of free carbon is used at a high temperature, the mechanical properties of the composite material deteriorate due to the carbide formation reaction, but when said silicon carbide fibers are coated with a metal or ceramic material and a composite material are made using such coated fibers as the reinforcing fibers, even if such a composite material is used at a high temperature for a long period of time, the inherent properties of the metal matrix can be maintained and the various excellent physical and chemical properties of the above described cohesive silicon carbide fibers are fully developed. The coating of the silicon carbide fibers described above with a metal, alloy or ceramic material can be accomplished in the following seven ways: (1) chemical vapor deposition, (2) flame melt spray coating, (3) spray coating, (4) steam coating, (5) electroplating , (6) powder firing, (7) non-electrode plating. (1) Chemical vapor deposition: Gas of metal compound alone or together with hydrogen gas, oxygen gas, CO2 gas, hydrocarbon gas or other gas is thermally decomposed at 500-2700 ° C to form the metal coating described above on the fiber surface. In the case of tungsten chloride and hydrogen, for example, a tungsten metal coating is formed from about SOOOC. When zirconium iodide gas is thermally decomposed at 1300-1800 ° C, a zirconium metal coating is formed. When a mixed gas of platinum chloride gas and CO gas is thermally decomposed, a platinum coating is formed. (2) Flame melt spray coating: A metal, alloy or ceramic material is melted with a high temperature flame, and the molten metal, alloy or ceramic material is sprayed on the silicon carbide fiber surface to form a coating film. As said flame, oxygen-acetylene gas flame and a plasma jet flame can be used. Laao1408-5 (3) Spray coating: In Argon plasma is formed by a high frequency outflow under argon atmosphere, and said plasma bombs a target of metal, alloy * or ceramic material to vaporize the metal, alloy or ceramic material to form the coating on silicon carbide - the fiber surface ((4) vacuum vapor coating: - A metal, alloy or ceramic material is heated and evaporated under vacuum to form the coating on the silicon carbide fiber surface. (5) Electroplating: An electrolyte containing a metal ion is subjected to electrolysis using the silicon carbide fibers (6) Powder burning: Finely divided powder of a metal, alloy or ceramic is prepared and the powder is suspended in a solvent, after which the silicon carbide fibers are immersed in the suspension to deposit the powder on the fibers. and heated to form the metal coating on silica gel the arbide fibers. (7) Non-electrode plating: the silicon carbide fiber surface is plated with a metal without the use of electrical energy through the use of a chemical exchange of mutual metals and a reduction function. The plating bath to be used in this plating consists of a metal salt, a reducing agent and a buffer solution.

Among ceramic coatings, an oxide coating can be obtained in six of the methods described above, excluding (5). In addition to the six methods described above, it is possible to form an oxide film by heating the silicon carbide fibers or silicon carbide fibers coated with a metal. or alloy, at high temperature. The oxide coating can be formed by heating such fibers at 500-2500 ° C for 0.1-50 hours under an oxidizing atmosphere. At a temperature below 500 ° C the oxidation temperature is low and the oxide coating is not completely formed, while at a temperature above 2500 ° C the decomposition and evaporation of silicon carbide progresses to a great extent, so the heating temperature must be 500-2500 ° C.

The heating time under oxidizing atmosphere is necessarily 30 hours at a temperature as low as 500 ° C, while at a temperature as high as 2500 ° C a good result can be achieved within 0.2 hours. As the oxidizing atmosphere is heated, air the most economical, and the oxide coating can be formed empty using a mixed gas of ozone and air.

If the heating described above is carried out under at least one atmosphere of nitrogen gas, ammonia gas and a mixed gas of ammonia and hydrogen, a metal nitride can be formed, and the heating temperature in this fail is preferably soo-2soo ° c.

If the silicon carbide fiber surface is coated with a metal or alloy, the wettability of the metal or alloy described above to the magnesium matrix is very good, since the contact angle of the mutual metals is less than 900 and is small. Accordingly, the coating of the silicon carbide fiber surface with a metal or alloy improves the wettability of magnesium alloy matrix to the silicon carbide fibers and is further effective in preventing the formation of carbides of the elements present in the metal matrix and adapted to form magnesium carbides. materials, produced in this way, are significantly improved.

When the metal elements of B, Mn, Mo, Al, W, Si, Cr, Ca, Ce, V, U, Th, Nb, Ta, Ti, Zr and Hf among the coated metals and alloys are heated together with the free carbon, stable carbides. Accordingly, the metal coating described above is completely or partially converted to the carbide coating by heating when the composite material is formed, and the carbide coating prevents the diffusion of the free carbon from the inner part of the silicon carbide fibers and the reaction of the free carbon with the magnesium alloy metal element to form the carbide.

The advantageous metals to be used for coating the silicon carbide fibers are, in addition to the metals described above, capable of forming the carbides, Be, Mg, Fe, Co, Ni, Cu, Zn, Ge, Pd, Ag, Cd, Sn, Sb, Pt, Au and Pb and alloys of at least two metal elements of the metal elements described above. The advantageous ceramic materials to be used for coating the silicon carbide fibers include MgO, Al 2 O 3, SiO 2, TiO 2 and ZnO as oxide and AlN, Mg 3 N 2, Si 3 N 4, TiN and ZrN as nitride and TiC, ZrC and WC as carbide.

When the thickness of the film coated on the silicon carbide fibers described above is less than 100 Å, the coated film is too thin and the effect of preventing the diffusion of the free carbon is weak, while at over 2000 Å the effect of preventing the diffusion of the free carbon does not differ. from the case where the thickness is at most 12 82- * 201408-5 2000 A, why such a large thickness is not necessary. Accordingly, the thickness of the film to transfer the silicon carbide fibers contains about 1-4% by weight of the free carbon, preferably 10 to 100 .mu.m.

The composite materials consisting of the silicon carbide fibers and magnesium alloy can be prepared in the following manner for the production of common metal composite materials reinforced with fibers, such as (1) diffusion bonding, (2) liquid infiltration, (3) melt spraying, (4) electrolytic precipitation, (5) and hot rolling,: (6) chemical vapor deposition, and '(7) cold pressing and sintering. (1) Diffusion bonding: The silicon carbide fibers and the matrix metal wires are arranged alternately in one direction, the upper surface and bottom surface of the stack of silicon carbide fibers and metal wires are coated with thin films of the matrix metal or only the bottom surface is coated with the film. to form composite layers, which layers are laminated in a few steps, and the formed laminate is then heated under pressure to form a composite material consisting of the silicon carbide fibers and the matrix metal. As the said organic binders, those substances which evaporate before heating to a temperature at which the matrix metal and the free carbon in the silicon carbide fibers react and form the carbide can be suitably used, for example starch, CNC, paraffin, resin, ammonium chloride, mineral oil, polyvinyl alcohol, polystyrene , organic polymers, etc.

Alternatively, the silicon carbide fibers, coated with matrix metal powder mixed with an organic binder, are arranged and stacked, and the formed laminate is pressed under heating to form a kempeeitmeteriei. (2) Liquid infiltration: The spaces between the arranged silicon carbide fibers are filled with molten magnesium alloy. In this case, since the wettability of the silicon carbide fibers, coated with the metal, to the matrix metal is good, the spaces between the arranged fibers can be carefully filled with the matrix metal. 13 azm 4os-s (3) Melt spraying: The surfaces of the arranged silicon carbide fibers are coated with the matrix metal by a plasma melting spray or a gas melting spraying to form a cone-shaped composite material. The cone-shaped composite material is used directly or the stacked composite materials are stacked, and the formed material is subjected to the diffusion bond (1) described above to form a composite material. (4) Electrolytic precipitation: The matrix metal is electrolytically deposited on the surfaces of the fibers to form a composite material, and it is further possible to arrange and stack the formed composite materials, and the formed laminate is subjected to the diffusion bond described above. (5) Hot extrusion and hot rolling: The silicon carbide fibers are arranged in one direction and the arranged silicon carbide fibers are arranged between matrix metal foils in a stacking ratio and then passed through heated rollers to bond the fibers and the matrix metal, forming a composite material. (6) Chemical vapor deposition: The silicon carbide fibers are charged into a heating furnace and, for example, a mixed gas of aluminum chloride and hydrogen gas is introduced into the furnace, whereby aluminum chloride is thermally decomposed to deposit aluminum metal on the surfaces of the silicon carbide fibers. In addition, the fibers with deposited metal can be arranged and stacked and the formed laminate exposed to the diffusion bond (1) described above. (7) Cold pressing and sintering: The spaces between the arranged fibers are filled with matrix metal powder and the joint is formed under pressure, after which the formed molding is heated and sintered with or without pressure to form a composite material. If the composite materials are prepared using the silicon carbide fibers coated with the metal or ceramic material, the seven methods (1) to (7) described above can be used.

The tensile strength (Oc) of the composite material produced from the silicon carbide fibers and the metal matrix is represented by the following formula (2). aan 1i4oses 14 '+ oMVM --- (2) Tensile strength of the composite material.

G O ll G Q 0 Ha <u n p "Tensile strength of SiC fibers.

Traction fracture limit of the metal matrix.

Vol% of SiC fibers.

VM: Vol% of the metal matrix.

Q H13 As can be seen from the formula (2) above, the tensile strength of the composite material becomes higher with increasing volume fraction of the silicon carbide fibers in the composite material. Consequently, the production of composite materials with a higher tensile strength requires an increase in the volume of the added silicon carbide fibers. However, when the amount of the silicon carbide fibers is greater than 70% by volume, the amount of the metal matrix is too small, so that it is impossible to completely fill the spaces between the silicon carbide fibers with the metal matrix and consequently impossible to develop the tensile strength stated by the formula ( 2) in the composite material formed. As the amount of fibers decreases, the tensile strength of the composite material decreases, so that at least 20% by volume of the silicon carbide fibers should be added to obtain the practically useful composite materials. In the production of the light metal composite material reinforced with the silicon carbide fibers of the present invention, the amount of silicon carbide fibers to be added must be 20-70% by volume. The modulus of elasticity (Ec) of the composite material is represented by the following formula (3).

W Il '<2 + VmEm ... (3) Modulus of elasticity of the composite material: Modulus of elasticity of Sic fibers. b! O »fn n.

P1 uph: Modulus of elasticity of the metal matrix.

Vol% of SiC fibers.

Vol% of the metal matrix. a <H14 ab! As can be seen from the formula above, the modulus of elasticity of the composite material increases with increasing amount of silicon carbide fibers to be added to the metal matrix. However, when the fiber content becomes too high, the toughness of the composite materials becomes poor, so that the composite materials become brittle and lack in reliability. EXAMPLE 1 'This example describes a process for producing continuous silicon carbide fibers to be used in the invention.

Dimethyldichlorosilane and sodium were reacted to form polydimethylsilane. 250 g of polydimethylsilane were charged to an autoclave with a capacity of 1 l, and air in the autoclave was replaced with argon gas, after which the reaction was carried out at 470 ° C for 14 hours. After complete reaction, the formed polycarbosilane was discharged as n-hexane solution.

This n-hexane solution was filtered to remove impurities after which the n-hexane was evaporated under reduced pressure. The residue was then heated in an oil bath at 280 ° C under vacuum for 2 hours to effect concentration. Polycarbosilane was obtained in a yield of 40%, based on dimethyldichlorosilane. The number average molecular weight of the formed polycarbosilane was 1700. Using a standard spinner, the polycarbosilane was heated and melted at 330 ° C under an argon atmosphere to form a spinning melt, and the spinning melt was spun at a spinning speed of 200 m / fibrose to obtain polycarbons. The fibers were heated by increasing the temperature from 20 to 190 ° C in air for 6 hours, and this temperature was maintained for 1 hour to carry out a non-melting treatment. The fibers thus treated were heated to 300 ° C at a temperature increase rate of 10 ° C / h under a vacuum of 1 x 10 -3 mm fl g, and this temperature was maintained for 1 hour to form SiC fibers. The SiC fibers formed had an average diameter of 10 μm, an average tensile strength of 350 kp / mm 2, an average modulus of elasticity of 23 x 10 3 kp / mm 2 and a specific gravity of 2.70 g / cm 3.

EXAMPLE 2 Magnesium alloy consisting of 10% by weight of aluminum, 0.5% by weight of manganese and the remainder magnesium was heated and melted in a chamber under an argon atmosphere at 100 ° C. A bundle of the silicon carbide fibers, each 10 .mu.m in diameter and containing 4% by weight of free carbon, was charged in parallel in a magnesium oxide tube, both ends of which were open, one end of the tube sealed and the other connected to a vacuum system. The tube was degassed under heating and introduced into the chamber under an argon atmosphere and the seal was removed. The open end of this magnesium oxide tube was immersed in the molten magnesium alloy described above and the other end was subjected to vacuum.

The molten magnesium alloy was drawn up into the magnesium oxide tube and filled the spaces between the silicon carbide fibers, and the molten state of the magnesium alloy was maintained for 30 minutes to obtain a magnesium alloy composite material reinforced with the silicon carbide fibers. The resulting composite material contained 25% by volume of the fibers and had a tensile strength of 73 kp / mm 2. This tensile strength was about 4 times as high as that of magnesium alloy without silicon carbide fibers. This result shows that the reinforcing effect of the silicon carbide fibers is fully developed, that the free carbon in the silicon carbide fibers reacts with aluminum in the magnesium alloy and that the wettability of the fibers to the metal matrix is good.

EXAMPLE 3 Magnesium alloy consisting of 93.4% by weight of magnesium, 0.6% by weight of zirconium, 2.0% by weight of yttrium and 4.0% by weight of zinc was heated and remelted chamber under argon atmosphere at 800 ° C. A bundle of the silicon carbide fibers, each with a diameter of 15 cm and containing 6% by weight of free carbon, was charged in parallel in a magnesium tube, both ends of which were open, and in the same manner as in Example 2, the spaces between the silicon carbide fibers were filled with the melting the magnesium alloy, and the molten state of magnesium alloy was maintained to obtain a magnesium alloy composite material reinforced with the silicon carbide fibers. The resulting composite material contained 32% by volume of the silicon carbide fibers and had a tensile strength of 87 kp / mm 2. The composite effect of the fibers and the metal was obvious and the free carbon in the fibers reacts with the added elements in the alloy to improve the wettability of the fibers to the alloy, and the property as a composite material is developed.

EXAMPLE 4 The silicon carbide fibers containing 5% by weight of free carbon were stacked in parallel, and the spaces between the silicon carbide fibers were filled with magnesium alloy powder consisting of 1.0% by weight of manganese, 0.1% by weight of calcium, 0.25% by weight of silicon, 0.03% by weight of copper, 0.008% by weight. % nickel, 0.20% by weight of another element and 98.412% by weight of magnesium to form a molding with the dimensions 20 nmlx 50 nmnx nmn This molding was subjected to hot pressing under a pressure of 0,5 ton / cm2 under an argon atmosphere at 550 ° C in 4 hours to obtain a magnesium alloy composite material reinforced with the silicon carbide fibers. The resulting composite material contained 30% by volume of the fibers and had a tensile strength of 30 kp / mm 2. This tensile strength is approximately 2 times higher than that of the magnesium alloy without fibers, so that the composite effect is obvious. This shows that the free carbon in the fibers reacts with the added elements of the magnesium alloy to improve the wettability of the fibers to the alloy.

Ezmnvm. A woven fabric consisting of silicon carbide fibers, each with a diameter of 10 .mu.m and containing 10% by weight of free carbon, was cut into sheets with a diameter of 100 mm. The formed discs were arranged with a pitch of 0.02 mm, and such arranged discs were introduced into a chamber under an argon atmosphere. Magnesium alloy consisting of 9.5% by weight of aluminum, 0.5% by weight of manganese, 2.1% by weight of zinc, 0.2% by weight of silicon, 0.1% by weight of copper, 0.05% by weight of nickel, 0.25% by weight of the other elements and 87.3% by weight of magnesium were charged into the chamber under an argon atmosphere and melted by heating at 80,000, and the molten alloy was poured onto the arranged woven fabrics of woven fibers described above. The molten state of the magnesium alloy was maintained for 30 minutes to obtain a magnesium alloy composite material reinforced with the silicon carbide fibers. The resulting composite material contained 25% by volume of the silicon carbide fibers and had a tensile strength of 65 kp / mm 2. This tensile strength was about 3 times as high as that of non-fibrous magnesium alloy. This shows that the free carbon reacts with the added elements in the alloy to improve the wettability of the fibers to the alloy. simmar. 6 in Magnesium alloy composite material was prepared from 60% by volume of magnesium alloy consisting of 3.0% by weight of aluminum, 1% by weight of manganese, 1.3% by weight of zinc and the remainder magnesium and 40% by volume of silicon carbide fibers containing 15% by weight of free carbon. The silicon carbide fibers (diameter 20 Pm) were coated with nickel, copper or 13% iron-chromium alloy to a thickness of about 800 Å by vacuum vapor coating.

The silicon carbide fibers with a diameter of 20 μm were heated at 110,000 in air for 1 hour to obtain with silica-coated silicon carbide fibers.

The surfaces of these fibers were coated with a mixture of powders of the above-described magnesium alloy (95% by weight) and paraffin (5% by weight) to an average thickness of 12 .mu.m, and the fibers thus treated were arranged and stacked in a dimene mold ions 20x50x30 mm and maintained at a pressure of 200 kp / mm 2 at 18 ° C for 480 ° C in an argon atmosphere for 1 hour to obtain magnesium alloy composite materials. The tensile strengths and modulus of elasticity of the composite materials are given in Table 1. f TABLE 1 - Coating material Nickel Copper 13% iron chromium S102 nšaghrahtgfshs, xp / mhz 95 99, of 'es zlasticicecs module, _ y y- ey 3103 hp / mm * 16 is 11 * rariahghihg, s - 1,5 1,2 1,6 1,8 fWith the magnesium alloy the tensile strength is 22 kp / mmz and the elasticity is 4,6x103 kp / mmz, and in comparison with these values was, as shown in Table 1 above, the tensile strength and the modulus of elasticity of magnesium alloy composite materials of the present invention are much higher. Even if the magnesium alloy composite materials were kept at 480 ° C for 50 hours, the properties did not decrease. Magnesium alloy composite materials reinforced with cohesive silicon carbide fibers obtained according to the present invention have very high tensile strength and high modulus of elasticity, so that the composite materials can be used as the following different materials. (a) Materials for the production of synthetic fibers: e bobine, separator, pump parts, ball, socket mechanical seal, valve, nozzle, stirrer, reaction vessel, tube, heat exchanger, etc. (b) -Materials for synthetic chemistry apparatus. piston pump, socket, mechanical seal, separator, reactor valve, reducer valve, seat, heat exchanger, centrifugal machine, low temperature vessel, etc. g ', (c) Mechanical industrial materials: l "heat exchanger, powder pressing nozzle, ultrasonic machine, hinging machine, sawing machine parts, cam, ball mill parts, camera parts, vacuum pump, collector, bearings, tools, bell parts, machine foundations, etc. _ l ka) Materials household and k ° ntpr = table, various shelves, chairs, various cabinets, etc. 19 8201408-5 (e) Materials for construction of machine: drill, stone crusher, Caterpillar, sand pump, excavator, etc. (f) Fire protection material: sprinkler, ladder, etc. (g) Marine (cosmic) materials: heat exchangers, antennas, buoys on water, tanks, etc. (h) Car parts: motor, manifold, transmission means for differential gearbox, shaft housing, pump housing, valve housing, clutch housing, transmission housing, gearbox, flywheel housing, cylinder block, cylinder head, piston, drive pulley, pump housing, fan housing, tire shape, rotary motor, construction material, body material, etc. (i) Materials for food production equipment: decanter, valve, reactor, mechanical seal, separator, etc. (j) Sporting goods: nails, golf articles, tennis racket, fishing tackle, mountaineering articles, ski articles, badminton racket, balls, etc. (k) Ship and aircraft material: engine, construction material, outer wall, screw, bearing surface in water, etc. (1) Electrical materials: transmission cable, capacitor, chassis, antennas, stereophonic parts, poles, etc. (m) Architectural material: window frame, construction material, etc. (n) Agricultural machinery, fishing gear, nuclear gear, nuclear fusion material, solar heat utilization material, medical instruments, bicycle material, valve, valve seat, ring, rod, disc, lining, sand transport pump parts, dust parts, nozzle and injection molding machine parts of plastics, reflecting mirrors, etc.

Claims (10)

20 8i201 4118-51 CLAIMS Magnesium alloy composite material, characterized in that it is reinforced with cohesive silicon carbide fibers, which are obtained by heating 20-80 vol% of magnesium alloy matrix and 80-20 vol% of cohesive silicon carbide fibers containing 0.01-40 wt. % free carbon at a temperature which melts the magnesium alloy. J S Magnesium alloy composite material according to claim 1, characterized in that the magnesium alloy consists of magnesium and at least one of aluminum, manganese, zirconium, calcium, silicon and yttrium. 3. 73. A method of producing magnesium alloy composite materials, reinforced cohesive silicon carbide fibers according to claim S1, characterized in that 80-20% by volume of the cohesive silicon carbide fibers containing 0,01 to 40% by weight of free carbon are combined with 20-80% by volume of molten magnesium alloy matrix to react the free carbon in the silicon carbide fibers with the metal elements present in the magnesium alloy which readily form carbides, to form carbides of these metals and to increase the wettability of the silicon carbide fibers to the metal matrix. 4. A method according to claim 3, characterized in that the metal element in the magnesium alloy, which easily forms the carbide with the free carbon, is aluminum, manganese, zirconium, silicon, calcium or yttrium. 5. A method according to claim 3, characterized in that the silicon carbide fibers containing 0.01-40% by weight of free carbon are first coated with metal and / or ceramic material, after which the coated fibers are combined with 20-80% by volume of molten magnesium alloy. 6. A method according to claim 5, characterized in that the coating metal is B, Mn, Mo, Al, W, Si, Cr, Ca, Ce, V, U, Th, Nb, Ta, Ti, Zr or Hf . S 7. A method according to claim 5, characterized in that the coating metal is Be, Mg, Fe, Co, Ni, Cu, Zn, Ge, Pd, Ag, Cd, Sn, Sb, Pt, Au, Pb or an alloy consisting of of at least two of these metal elements. 'B. 8. A method according to claim 5, characterized in that the ceramic material is Mg0, Al2O3, TiO2, ZnO, AlN, Mg2N2, Si3N4, TiN, ZrN, Tic, ZrC or WC. - d N 8201408-5 9. A method according to claim 5, characterized in that the coating with metal or ceramic material is made to a thickness of 100-2000 Å. 10. A method according to claim 5, characterized in that the coating is achieved by chemical vapor deposition, flame melt spray coating, spray coating, vacuum vapor coating, electroplating, powder firing or non-electrode plating.